Acid and vitamin E: Trimethylsilyl super Lewis acids, such as [C6F5C(Tf)2]− Me3Si+ and Tf3CSiMe3, are extremely active and highly effective catalysts for the regioselective condensation of trimethylhydroquinone with isophthyol to afford (±)‐α‐tocopherol (vitamin E; see scheme, Tf=CF3SO2.

[Structure: see text] A new Brønsted acid-assisted chiral Brønsted (chiral BBA) acid catalyst (1) was developed by substituting a hydroxy group of optically active 1,1'-bi(2-naphthol) with a stronger Brønsted acidic group such as a bis(trifluoromethanesulfonyl)methyl group. The enantioselective Mannich-type reaction of ketene silyl acetals with aldimines catalyzed by (R)-1 in the presence of stoichiometric achiral proton sources gave (S)-beta-amino esters in high yield with moderate to good enantiomeric excesses.

Various arylbis(trifluoromethylsulfonyl)methanes (1) have been synthesized by reacting the corresponding benzylic halides with sodium trifluoromethanesulfinate and then with triflic anhydride. In addition, when the aryl group of 1 is a pentafluorophenyl group, the nucleophilic para-substitution of the aryl group with alkyllithiums and sodium alkoxides occurs. This reaction is useful for the design of new Brønsted acids.

Several advantages over inorganic solid acids such as zeolites and perfluororesinsulfonic acids such as Nafion are offered by the new reusable polystyrene‐bound catalyst 1: a broader range of applications, improved yields, improved selectivity, and milder reaction conditions. Tf = F3CSO2.

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Perfluororesinsulfonic acids such as Nafion are highly acidic solid catalysts, and they are superior to conventional resinsulfonic acids such as Dowex-50, Amberlite IR-112, and Permutit-Q with regard to catalytic activity, thermal stability, and chemical resistance. [1, 2] However, like inorganic solid acids such as zeolites, they are not effectively swollen by most aprotic organic solvents. [3] A resin-bound superacidic Brùnsted acid that is effectively swollen by such solvents may offer several advantages over Nafion, including a broader range of applications, improved yields, improved selectivity, and milder reaction conditions.The trifluoromethanesulfonyl (triflyl, Tf) group is one of the strongest neutral electron-withdrawing groups. [4] In particular, it greatly increases the acidity of a-hydrogen atoms. [5±7] For example, phenylbis(triflyl)methane (1, pK a 7.83 in MeCN) [6] is a strong nonoxidizing acid. The steric and electronic effects of the aromatic ring in arylbis(triflyl)methanes are expected to greatly influence their Brùnsted acidity and their catalytic activity and selectivity for organic reactions. We report here on concise syntheses of the new strong organic Brùnsted acids pentafluorophenylbis(triflyl)methane (2) and polystyrene-bound tetrafluorophenylbis(triflyl)methane (3) and their catalytic applications in organic synthesis.

A new synthetic process was developed for (+)-2-((1R,2R,3R,5S)-2-amino-6,6-dimethylbicyclo[3.1.1]hept-3-yl)ethanol, a key intermediate of S-5751. Diastereoselective alkylation of (+)-nopinone with ethyl bromoacetate, formation of O-methyl oxime, and diastereoselective reduction with NaBH 4 -AlCl 3 could be safely carried out. Stereochemistry of the (1R,2R,3R,5S)-6,6-dimethylbicyclo[3.1.1]heptane ring was discussed to achieve high diastereoselectivity on these reactions. For the scale-up, detailed consideration was given to the safety of the NaBH 4 -AlCl 3 reduction.

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